Method and apparatus for adding CSG identities to a white list in connected mode

ABSTRACT

A serving eNodeB and a method thereof are provided. The serving eNodeB includes a receiver configured to receive, from a wireless transmit/receive unit (WTRU), a first measurement report including a physical layer cell identity (PCI) of a target closed subscriber group (CSG) cell detected by the WTRU, a transmitter configured to, in response to the received first measurement report, to transmit a message to the WTRU indicating that the WTRU is to read system information (SI) of the target CSG cell, and a processor. The receiver is further configured to, in response to a transmission of the message, receive a second measurement report for the target CSG cell including information read from the SI, and the processor is configured to, in response to receipt of the second measurement report, add the target CSG cell to a cell list and initiate a handover of the WTRU to the target CSG cell.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.12/986,961 filed Jan. 7, 2011, which issued on Oct. 11, 2016 as U.S.Pat. No. 9,467,884, which claims the benefit of U.S. ProvisionalApplication No. 61/293,562, filed on Jan. 8, 2010, and U.S. ProvisionalApplication No. 61/329,481, filed on Apr. 29, 2010, the contents ofwhich are hereby incorporated by reference herein.

FIELD OF INVENTION

This application is related to wireless communications.

BACKGROUND

Home Node Bs (HNBs) for Universal Mobile Telecommunications System(UMTS) and Home evolved Node Bs (HeNBs) for Long Term Evolution (LTE),hereinafter, interchangeably referred to as HNBs or HeNBs, have beenintroduced in LTE to increase the cellular coverage and the overallsystem throughput. The HNBs may have a dense deployment and may be inthe coverage area of one or more macro Node Bs. For example, they may beused in a private house or in a coffee shop. An IDLE mode mobility(IDLE, cell paging channel (CELL_PCH), and URA_PCH for UMTS and IDLE forLTE) has been standardized. Standardizing a connected mode mobility(i.e., handover) for Release 9 has not been completed.

The HNB refers to a physical device that may be similar to a wirelesslocal area network (WLAN) access point (AP). The HNB provides users withaccess to UMTS and/or LTE services over extremely small service areas,such as homes or small offices. The HNB is intended to connect to theoperators' core network by using, for example, an internet connection(e.g., digital subscriber line (DSL)).

A HNB closed subscriber group (CSG) cell is a defined area over whichradio coverage provided by the HNB may only be accessed by a group ofsubscribers authorized to use the services of the cell. The authorizedwireless transmit/receive units (WTRUs) are called members of the CSGcell. The CSG may be a family or anyone in the vicinity of a particularlocation (e.g., anyone in a coffee shop) who attempts to access the HNBCSG cell. The subscriber (i.e., the WTRU) who may be an individual or anorganization may deploy a CSG cell using a HNB over an area where suchservice is desired. Each WTRU stores a list, referred to herein as awhite list or allowed list, which includes CSG identities (IDs) of theCSG cells it is authorized to access. A hybrid cell is a cell that workssimilar to a CSG cell for member WTRUs and similar to an open cell fornon-member WTRUs, but may prioritize access for member WTRUs.

In wireless communication systems, various mobile devices, such as cellphones and other user equipment (UE), or a WTRU may be in connectionwith and served by a base station such as a HNB. A HeNB may serve as abase station/cell and may provide coverage over smaller areas than macrocells may provide in 3G, LTE, or other systems, for example.

FIG. 1 shows an example of a conventional HeNB deployment in a wirelesscommunication system 100. The wireless communication system 100 includesan LTE macro cell 105, a 3GPP system cell 110, a higher network node(e.g., gateway) 115 and/or a mobility management entity (MME)/servinggeneral packet radio service (GPRS) support node (SGSN) 120. The highernetwork node 115 is responsible for coordinating the operation ofseveral HeNBs 125A, 125B and 125C. Alternatively, the MME/SGSN 120 maybe responsible for coordinating the operation of HeNBs 125A, 125B and125C. The MME is the LTE equivalent of a 3G/2G SGSN. The relationshipbetween the LTE macro cell 105 and the 3GPP system 110, (e.g., widebandcode division multiple access (WCDMA)/global system for mobilecommunications (GSM)), is that there may be areas where the coverage ofthese two technologies overlap. This overlap in coverage is similar tosimultaneous coverage of GSM and WCDMA technologies. The higher networknode 115 is likely to be a gateway function which interfaces with theMME/SGSN 120. As a gateway, the role of the higher network node 115 maybe to act as a single macro cell towards the MME/SGSN 120 whilesupporting several small home cells.

FIG. 2 shows an LTE wireless communication system 200 including a WTRU205, a serving CSG cell 210, and a neighbor CSG cell 215. To complete aninbound handover to a CSG cell in the LTE wireless communication system200, the WTRU 205 needs to measure and report the CSG cell to thenetwork. However, CSG cells are prone to physical layer cell identity(PCI) confusion, which is when two different CSG cells in theneighborhood of a radio network controller (RNC) or eNB, where the WTRUis initially connected, utilize the same PCI. PCI confusion may alsoexist if the WTRU has to handover to a CSG cell which it is not a memberof (e.g., hybrid cell).

A HeNB may be an open node, a restricted access node, or a hybrid node,among others. A restricted access node HeNB may permit connection with aWTRU that is a member of a CSG of that node. In other words, if arestricted access HeNB node does not recognize the WTRU attempting toconnect as a member of the node's CSG, the HeNB may not accept theconnection, which may include a handover attempt from another HeNB. Asindicated, an example of a restricted access HeNB may be a HeNB thatbelongs to a CSG. A CSG HeNB may provide access and service to a WTRU ona subscription (or membership) basis. Further, a CSG HeNB may be a CSGcell. A CSG cell may also include a CSG macro cell or CSG macro node B,among others. An open node or open HeNB may be a non-CSG cell.

The hybrid type HeNB may accept a connection with a WTRU that is not anidentified member of the CSG to which the hybrid HeNB belongs, but thenon-member WTRU connection with the hybrid HeNB may be subject tocertain limitations. For example, the hybrid HeNB may deny thenon-member WTRU a preferential rate or the non-member WTRU may bepreempted before the member WTRU, should the hybrid HeNB need to preemptnon-member WTRU due to a quality of service issue. A hybrid HeNB may bea hybrid cell. A hybrid cell may also include a hybrid macro cell or ahybrid node B, and the like.

At times, and for various reasons, a WTRU may need to transfer from oneHeNB to another HeNB, or from one cell to another cell. For example, ina handover, a WTRU may replace a connection to one HeNB or cell with aconnection to second HeNB cell. If the second HeNB is a CSG cell (or CSGHeNB, close mode cell, or CSG cell), the CSG cell may not accept aconnection to a WTRU that the CSG cell does not recognize as a CSGmember WTRU. In such situations, the handover may fail. A method andapparatus that allow the WTRU to search and add one or more CSG IDs inthe WTRU white list while in connected mode are desired.

SUMMARY

A method and apparatus are provided that allow the WTRU to search andadd one or more CSG IDs in the WTRU white list while in connected mode.Such method and apparatus include but are not limited to WTRU autonomoussearch or a manual search, WTRU initiated procedures, or networkinitiated procedures. Additionally, methods that allow the networkand/or the non-access stratum (NAS) to add CSG IDs are also described.

A method and a WTRU is provided comprising a processor configured todetect a trigger for starting an autonomous CSG cell search forneighboring CSG cells, a transmitter configured to send a message to anetwork indicating that the autonomous CSG cell search in connected modehas began, a receiver configured to receive a message from the networkindicating a request for detecting, measuring, and reporting theneighboring CSG cells, and the processor configured to detect andmeasuring the neighboring CSG cells.

An MME comprising a processor configured to determine a status of a WTRUrelative to a target CSG cell, determine whether the WTRU hastransferred from a source home NodeB (HNB) to the target CSG cell, andon a condition that the WTRU has transferred from a source HNB to thetarget CSG cell, update the source HNB with a current identification ofthe target CSG cell is provided.

BRIEF DESCRIPTION OF THE DRAWINGS

A more detailed understanding may be had from the following description,given by way of example in conjunction with the accompanying drawingswherein:

FIG. 1 shows an example of a conventional HeNB deployment in a wirelesscommunication system;

FIG. 2 shows an LTE wireless communication system in accordance with oneembodiment;

FIG. 3A is a system diagram of an example communications system in whichone or more disclosed embodiments may be implemented;

FIG. 3B is a system diagram of an example a WTRU that may be used withinthe communications system illustrated in FIG. 3A;

FIG. 3C is a system diagram of an example radio access network and anexample core network that may be used within the communications systemillustrated in FIG. 3A;

FIG. 4 shows an LTE wireless communication system/access network;

FIG. 5 shows an example of an LTE wireless communication system shown inFIG. 4;

FIG. 6 illustrates a flow diagram of a procedure for adding CSG IDs to awhite list in a connected mode;

FIG. 7 illustrates a flow diagram of a procedure for to transfer aconnection to a CSG node of a communication network in accordance withan embodiment; and

FIG. 8 illustrates a flow diagram of a procedure to transfer aconnection to a CSG node of a communication network in accordance withanother embodiment.

DETAILED DESCRIPTION

When referred to hereafter, the terminology “wireless transmit/receiveunit (WTRU)” includes but is not limited to a user equipment (UE), amobile station, a fixed or mobile subscriber unit, a pager, a cellulartelephone, a personal digital assistant (PDA), a computer, or any othertype of user device capable of operating in a wireless environment. Whenreferred to hereafter, the terminology “base station” includes but isnot limited to a Node-B, a site controller, an access point (AP), HomeNode B, or any other type of interfacing device capable of operating ina wireless environment.

A HeNB may comprise a processor for processing data and commands, atransmitter for sending information, a receiver for receiving data, andan antenna coupled to the transmitter and the receiver for receivingstat across the wireless interface.

In wireless communication systems, a WTRU may be in connection with anHeNB that provides the WTRU with base station cell coverage. Such anHeNB may be referred to as a source or home HeNB and the source HeNB maybe a macro cell node, a CSG cell, or a hybrid node. The wirelesscommunication system may also include one or more a MME and at least oneother HeNB or cell.

It is understood that the concepts described herein are also applicableto other wireless technologies such as an UMTS. For the case of UMTS,the equivalent terminology for PCI may be primary scrambling code (PSC).

When referred to hereafter, signal “quality” may refer to a measurementtaken by the WTRU that measures the quality of the signal from a cell orthat measures the received signal level from a cell. This may correspondto reference signal receive quality (RSRQ) in LTE or common pilotchannel (CPICH) Ec/No in UMTS. It may also correspond to referencesignal receive power (RSRP) in LTE or CPICH received signal code power(RSCP) in UMTS. When referred to hereafter, CSG ID refers to CSGidentity and CGI refers to cell global identity.

FIG. 3A is a diagram of an example communications system 300 in whichone or more disclosed embodiments may be implemented. The communicationssystem 300 may be a multiple access system that provides content, suchas voice, data, video, messaging, broadcast, etc., to multiple wirelessusers. The communications system 300 may enable multiple wireless usersto access such content through the sharing of system resources,including wireless bandwidth. For example, the communications systems300 may employ one or more channel access methods, such as code divisionmultiple access (CDMA), time division multiple access (TDMA), frequencydivision multiple access (FDMA), orthogonal FDMA (OFDMA), single-carrierFDMA (SC-FDMA), and the like.

As shown in FIG. 3A, the communications system 300 may include WTRUs 302a, 302 b, 302 c, 302 d, a radio access network (RAN) 304, a core network306, a public switched telephone network (PSTN) 308, the Internet 310,and other networks 312, though it will be appreciated that the disclosedembodiments contemplate any number of WTRUs, base stations, networks,and/or network elements. Each of the WTRUs 302 a, 302 b, 302 c, 302 dmay be any type of device configured to operate and/or communicate in awireless environment. By way of example, the WTRUs 302 a, 302 b, 302 c,302 d may be configured to transmit and/or receive wireless signals andmay include user equipment (UE), a mobile station, a fixed or mobilesubscriber unit, a pager, a cellular telephone, a personal digitalassistant (PDA), a smartphone, a laptop, a netbook, a personal computer,a wireless sensor, consumer electronics, and the like.

The communications systems 300 may also include a base station 314 a anda base station 314 b. Each of the base stations 314 a, 314 b may be anytype of device configured to wirelessly interface with at least one ofthe WTRUs 302 a, 302 b, 302 c, 302 d to facilitate access to one or morecommunication networks, such as the core network 306, the Internet 310,and/or the networks 312. By way of example, the base stations 314 a, 314b may be a base transceiver station (BTS), a Node-B, an eNode B, a HomeNode B, a Home eNode B, a site controller, an access point (AP), awireless router, and the like. While the base stations 314 a, 314 b areeach depicted as a single element, it will be appreciated that the basestations 314 a, 314 b may include any number of interconnected basestations and/or network elements.

The base station 314 a may be part of the RAN 304, which may alsoinclude other base stations and/or network elements (not shown), such asa base station controller (BSC), a radio network controller (RNC), relaynodes, etc. The base station 314 a and/or the base station 314 b may beconfigured to transmit and/or receive wireless signals within aparticular geographic region, which may be referred to as a cell (notshown). The cell may further be divided into cell sectors. For example,the cell associated with the base station 314 a may be divided intothree sectors. Thus, in one embodiment, the base station 314 a mayinclude three transceivers, i.e., one for each sector of the cell. Inanother embodiment, the base station 314 a may employ multiple-inputmultiple output (MIMO) technology and, therefore, may utilize multipletransceivers for each sector of the cell.

The base stations 314 a, 314 b may communicate with one or more of theWTRUs 302 a, 302 b, 302 c, 302 d over an air interface 316, which may beany suitable wireless communication link (e.g., radio frequency (RF),microwave, infrared (IR), ultraviolet (UV), visible light, etc.). Theair interface 316 may be established using any suitable radio accesstechnology (RAT).

More specifically, as noted above, the communications system 300 may bea multiple access system and may employ one or more channel accessschemes, such as CDMA, TDMA, FDMA, OFDMA, SC-FDMA, and the like. Forexample, the base station 314 a in the RAN 304 and the WTRUs 302 a, 302b, 302 c may implement a radio technology such as Universal MobileTelecommunications System (UMTS) Terrestrial Radio Access (UTRA), whichmay establish the air interface 316 using WCDMA. WCDMA may includecommunication protocols such as High-Speed Packet Access (HSPA) and/orEvolved HSPA (HSPA+). HSPA may include High-Speed Downlink Packet Access(HSDPA) and/or High-Speed Uplink Packet Access (HSUPA).

In another embodiment, the base station 314 a and the WTRUs 302 a, 302b, 302 c may implement a radio technology such as Evolved UMTSTerrestrial Radio Access (E-UTRA), which may establish the air interface316 using LTE and/or LTE-Advanced (LTE-A).

In other embodiments, the base station 314 a and the WTRUs 302 a, 302 b,302 c may implement radio technologies such as IEEE 802.16 (i.e.,Worldwide Interoperability for Microwave Access (WiMAX)), CDMA2000,CDMA2000 1×, CDMA2000 EV-DO, Interim Standard 2000 (IS-2000), InterimStandard 95 (IS-95), Interim Standard 856 (IS-856), Global System forMobile communications (GSM), Enhanced Data rates for GSM Evolution(EDGE), GSM EDGE (GERAN), and the like.

The base station 314 b in FIG. 3A may be a wireless router, Home Node B,Home eNode B, or access point, for example, and may utilize any suitableRAT for facilitating wireless connectivity in a localized area, such asa place of business, a home, a vehicle, a campus, and the like. In oneembodiment, the base station 314 b and the WTRUs 302 c, 302 d mayimplement a radio technology such as IEEE 802.11 to establish a wirelesslocal area network (WLAN). In another embodiment, the base station 314 band the WTRUs 302 c, 302 d may implement a radio technology such as IEEE802.15 to establish a wireless personal area network (WPAN). In yetanother embodiment, the base station 314 b and the WTRUs 302 c, 302 dmay utilize a cellular-based RAT (e.g., WCDMA, CDMA2000, GSM, LTE,LTE-A, etc.) to establish a picocell or femtocell. As shown in FIG. 3A,the base station 314 b may have a direct connection to the Internet 310.Thus, the base station 314 b may not be required to access the Internet310 via the core network 306.

The RAN 304 may be in communication with the core network 306, which maybe any type of network configured to provide voice, data, applications,and/or voice over internet protocol (VoIP) services to one or more ofthe WTRUs 302 a, 302 b, 302 c, 302 d. For example, the core network 306may provide call control, billing services, mobile location-basedservices, pre-paid calling, Internet connectivity, video distribution,etc., and/or perform high-level security functions, such as userauthentication. Although not shown in FIG. 3A, it will be appreciatedthat the RAN 304 and/or the core network 306 may be in direct orindirect communication with other RANs that employ the same RAT as theRAN 304 or a different RAT. For example, in addition to being connectedto the RAN 304, which may be utilizing an E-UTRA radio technology, thecore network 306 may also be in communication with another RAN (notshown) employing a GSM radio technology.

The core network 306 may also serve as a gateway for the WTRUs 302 a,302 b, 302 c, 302 d to access the PSTN 308, the Internet 310, and/orother networks 312. The PSTN 308 may include circuit-switched telephonenetworks that provide plain old telephone service (POTS). The Internet310 may include a global system of interconnected computer networks anddevices that use common communication protocols, such as thetransmission control protocol (TCP), user datagram protocol (UDP) andthe internet protocol (IP) in the TCP/IP internet protocol suite. Thenetworks 312 may include wired or wireless communications networks ownedand/or operated by other service providers. For example, the networks312 may include another core network connected to one or more RANs,which may employ the same RAT as the RAN 304 or a different RAT.

Some or all of the WTRUs 302 a, 302 b, 302 c, 302 d in thecommunications system 300 may include multi-mode capabilities, i.e., theWTRUs 302 a, 302 b, 302 c, 302 d may include multiple transceivers forcommunicating with different wireless networks over different wirelesslinks. For example, the WTRU 302 c shown in FIG. 3A may be configured tocommunicate with the base station 314 a, which may employ acellular-based radio technology, and with the base station 314 b, whichmay employ an IEEE 802 radio technology.

FIG. 3B is a system diagram of an example WTRU 302. As shown in FIG. 3B,the WTRU 302 may include a processor 318, a transceiver 320, atransmit/receive element 322, a speaker/microphone 324, a keypad 326, adisplay/touchpad 328, non-removable memory 330, removable memory 332, apower source 334, a global positioning system (GPS) chipset 336, andother peripherals 338. It will be appreciated that the WTRU 302 mayinclude any sub-combination of the foregoing elements while remainingconsistent with an embodiment.

The processor 318 may be a general purpose processor, a special purposeprocessor, a conventional processor, a digital signal processor (DSP), aplurality of microprocessors, one or more microprocessors in associationwith a DSP core, a controller, a microcontroller, Application SpecificIntegrated Circuits (ASICs), Field Programmable Gate Array (FPGAs)circuits, any other type of integrated circuit (IC), a state machine,and the like. The processor 318 may perform signal coding, dataprocessing, power control, input/output processing, and/or any otherfunctionality that enables the WTRU 302 to operate in a wirelessenvironment. The processor 318 may be coupled to the transceiver 320,which may be coupled to the transmit/receive element 322. While FIG. 3Bdepicts the processor 318 and the transceiver 320 as separatecomponents, it will be appreciated that the processor 318 and thetransceiver 320 may be integrated together in an electronic package orchip.

The transmit/receive element 322 may be configured to transmit signalsto, or receive signals from, a base station (e.g., the base station 314a) over the air interface 316. For example, in one embodiment, thetransmit/receive element 322 may be an antenna configured to transmitand/or receive RF signals. In another embodiment, the transmit/receiveelement 322 may be an emitter/detector configured to transmit and/orreceive IR, UV, or visible light signals, for example. In yet anotherembodiment, the transmit/receive element 322 may be configured totransmit and receive both RF and light signals. It will be appreciatedthat the transmit/receive element 322 may be configured to transmitand/or receive any combination of wireless signals.

In addition, although the transmit/receive element 322 is depicted inFIG. 3B as a single element, the WTRU 302 may include any number oftransmit/receive elements 322. More specifically, the WTRU 302 mayemploy MIMO technology. Thus, in one embodiment, the WTRU 302 mayinclude two or more transmit/receive elements 322 (e.g., multipleantennas) for transmitting and receiving wireless signals over the airinterface 316.

The transceiver 320 may be configured to modulate the signals that areto be transmitted by the transmit/receive element 322 and to demodulatethe signals that are received by the transmit/receive element 322. Asnoted above, the WTRU 302 may have multi-mode capabilities. Thus, thetransceiver 320 may include multiple transceivers for enabling the WTRU302 to communicate via multiple RATs, such as UTRA and IEEE 802.11, forexample.

The processor 318 of the WTRU 302 may be coupled to, and may receiveuser input data from, the speaker/microphone 324, the keypad 326, and/orthe display/touchpad 328 (e.g., a liquid crystal display (LCD) displayunit or organic light-emitting diode (OLED) display unit). The processor318 may also output user data to the speaker/microphone 324, the keypad326, and/or the display/touchpad 328. In addition, the processor 318 mayaccess information from, and store data in, any type of suitable memory,such as the non-removable memory 330 and/or the removable memory 332.The non-removable memory 330 may include random-access memory (RAM),read-only memory (ROM), a hard disk, or any other type of memory storagedevice. The removable memory 332 may include a subscriber identitymodule (SIM) card, a memory stick, a secure digital (SD) memory card,and the like. In other embodiments, the processor 318 may accessinformation from, and store data in, memory that is not physicallylocated on the WTRU 302, such as on a server or a home computer (notshown).

The processor 318 may receive power from the power source 334, and maybe configured to distribute and/or control the power to the othercomponents in the WTRU 302. The power source 334 may be any suitabledevice for powering the WTRU 302. For example, the power source 334 mayinclude one or more dry cell batteries (e.g., nickel-cadmium (NiCd),nickel-zinc (NiZn), nickel metal hydride (NiMH), lithium-ion (Li-ion),etc.), solar cells, fuel cells, and the like.

The processor 318 may also be coupled to the GPS chipset 336, which maybe configured to provide location information (e.g., longitude andlatitude) regarding the current location of the WTRU 302. In additionto, or in lieu of, the information from the GPS chipset 336, the WTRU302 may receive location information over the air interface 316 from abase station (e.g., base stations 314 a, 314 b) and/or determine itslocation based on the timing of the signals being received from two ormore nearby base stations. It will be appreciated that the WTRU 302 mayacquire location information by way of any suitablelocation-determination method while remaining consistent with anembodiment.

The processor 318 may further be coupled to other peripherals 338, whichmay include one or more software and/or hardware modules that provideadditional features, functionality and/or wired or wirelessconnectivity. For example, the peripherals 338 may include anaccelerometer, an e-compass, a satellite transceiver, a digital camera(for photographs or video), a universal serial bus (USB) port, avibration device, a television transceiver, a hands free headset, aBluetooth® module, a frequency modulated (FM) radio unit, a digitalmusic player, a media player, a video game player module, an Internetbrowser, and the like.

FIG. 3C is a system diagram of the RAN 304 and the core network 306according to an embodiment. As noted above, the RAN 304 may employ anE-UTRA radio technology to communicate with the WTRUs 302 a, 302 b, 302c over the air interface 316. The RAN 304 may also be in communicationwith the core network 306.

The RAN 304 may include eNode-Bs 340 a, 340 b, 340 c, though it will beappreciated that the RAN 304 may include any number of eNode-Bs whileremaining consistent with an embodiment. The eNode-Bs 340 a, 340 b, 340c may each include one or more transceivers for communicating with theWTRUs 302 a, 302 b, 302 c over the air interface 316. In one embodiment,the eNode-Bs 340 a, 340 b, 340 c may implement MIMO technology. Thus,the eNode-B 340 a, for example, may use multiple antennas to transmitwireless signals to, and receive wireless signals from, the WTRU 302 a.

Each of the eNode-Bs 340 a, 340 b, 340 c may be associated with aparticular cell (not shown) and may be configured to handle radioresource management decisions, handover decisions, scheduling of usersin the uplink and/or downlink, and the like. As shown in FIG. 3C, theeNode-Bs 340 a, 340 b, 340 c may communicate with one another over an X2interface.

The core network 306 shown in FIG. 3C may include a MME 342, a servinggateway 344, and a packet data network (PDN) gateway 346. While each ofthe foregoing elements are depicted as part of the core network 306, itwill be appreciated that any one of these elements may be owned and/oroperated by an entity other than the core network operator.

The MME 342 may be connected to each of the eNode-Bs 340 a, 340 b, 340 cin the RAN 304 via an S1 interface and may serve as a control node. Forexample, the MME 342 may be responsible for authenticating users of theWTRUs 302 a, 302 b, 302 c, bearer activation/deactivation, selecting aparticular serving gateway during an initial attach of the WTRUs 302 a,302 b, 302 c, and the like. The MME 342 may also provide a control planefunction for switching between the RAN 304 and other RANs (not shown)that employ other radio technologies, such as GSM or WCDMA.

The serving gateway 344 may be connected to each of the eNode Bs 340 a,340 b, 340 c in the RAN 304 via the S1 interface. The serving gateway344 may generally route and forward user data packets to/from the WTRUs302 a, 302 b, 302 c. The serving gateway 344 may also perform otherfunctions, such as anchoring user planes during inter-eNode B handovers,triggering paging when downlink data is available for the WTRUs 302 a,302 b, 302 c, managing and storing contexts of the WTRUs 302 a, 302 b,302 c, and the like.

The serving gateway 344 may also be connected to the PDN gateway 346,which may provide the WTRUs 302 a, 302 b, 302 c with access topacket-switched networks, such as the Internet 310, to facilitatecommunications between the WTRUs 302 a, 302 b, 302 c and IP-enableddevices.

The core network 306 may facilitate communications with other networks.For example, the core network 306 may provide the WTRUs 302 a, 302 b,302 c with access to circuit-switched networks, such as the PSTN 308, tofacilitate communications between the WTRUs 302 a, 302 b, 302 c andtraditional land-line communications devices. For example, the corenetwork 306 may include, or may communicate with, an IP gateway (e.g.,an IP multimedia subsystem (IMS) server) that serves as an interfacebetween the core network 306 and the PSTN 308. In addition, the corenetwork 306 may provide the WTRUs 302 a, 302 b, 302 c with access to thenetworks 312, which may include other wired or wireless networks thatare owned and/or operated by other service providers.

FIG. 4 shows an LTE wireless communication system/access network 400that includes an Evolved-Universal Terrestrial Radio Access Network(E-UTRAN) 405. The E-UTRAN 405 includes several evolved Node-Bs, (eNBs)420 and HeNBs 460. The WTRU 410 is in communication with an eNB 420 anda HeNB 460. The eNBs 420 interface with each other using an X2interface. Each of the eNBs 420 interface with a MME/serving GateWay(S-GW) 430 through an S1 interface. The HeNBs 460 are also connected toa HeNB Gateway (HeNB GW) 470 through a S1 interface. The HeNB 460 andthe HeNB GW 470 connect to the MME/S-GW 430 through the S1 interface.The HeNB GW 470 appears to the MME/S-GW 430 as an eNB 420. The HeNB GW470 appears to the HeNB 460 as an MME/S-GW 430.

Although a single WTRU 410, three eNBs 420 and three HeNBs 460 are shownin FIG. 4, it should be apparent that any combination of wireless andwired devices may be included in the wireless communicationsystem/access network 400.

FIG. 5 shows an example of an LTE wireless communication system 500including the WTRU 410, the eNB 420, and the MME/S-GW 430. As shown inFIG. 5, the WTRU 410, the eNB 420 and the MME/S-GW 430 are configured toperform a method for adding CSG IDs to a white list in connected mode.

In addition to the components that may be found in a typical WTRU, theWTRU 410 includes a processor 516 with an optional linked memory 522, atleast one transceiver 514, an optional battery 520, and an antenna 518.The processor 516 is configured to perform a method of resolving PCIconfusion for inbound mobility to CSG cell and hybrid cell. Thetransceiver 514 is in communication with the processor 516 and theantenna 518 to facilitate the transmission and reception of wirelesscommunications. In case a battery 520 is used in the WTRU 410, it powersthe transceiver 514 and the processor 516.

In addition to the components that may be found in a typical eNB, theeNB 420 includes a processor 517 with an optional linked memory 515,transceivers 519, and antennas 521. The processor 517 is configured toperform a method of resolving PCI confusion for inbound mobility to aCSG cell and a hybrid cell.

The transceivers 519 are in communication with the processor 517 andantennas 521 to facilitate the transmission and reception of wirelesscommunications. The eNB 420 is connected to the MME/S-GW 430 whichincludes a processor 533 with an optional linked memory 534. TheMME/S-GW 430, eNB 420, and WTRU 410 are in communication with the HeNB460.

Inbound mobility, which refers to a handover from a macro cell to a HNB,may apply to intra-frequency scenarios (i.e., macro cell and HNB are onthe same frequency) as well as for inter-frequency scenarios (i.e.,macro cell and HNB are on different frequencies) both for UMTS and LTE.Inbound mobility inside the same RAT (e.g., UMTS or LTE) may beaccomplished in any of the following ways. These examples are notexhaustive and one skilled in the art may recognize that other ways arealso possible.

In one example, PSC/PCI confusion, due to HNBs using the same PCI/PSC,may be resolved by having the WTRU read the SI (SI) of the HNB to getthe cell identity (E-CGI/tracking area identity (TAI) for LTE) of theHNB and report it to the network.

In another example, the WTRU may perform a preliminary access check, acheck that the CSG ID of the HNB is part of the WTRU white list, beforereporting the HNB to the network. The network may only have to initiatethe handover preparation for the cells for which the WTRU has verifiedthe CSG ID.

In another example, cells may broadcast the PSC/PCI split of the CSGcells but may not broadcast the PSC/PCI split of the hybrid cells.

In another example, UMTS inter-frequency and LTE inter-frequency PSC/PCIdetection for non-CSG member WTRUs will not require any particularmechanisms. In order to perform PSC/PCI detection for CSG member WTRUsmay use compressed mode (CM)/measurement gaps that may be triggeredbased on a WTRU indication (e.g., based on a fingerprint or manualsearch). Fingerprint may be referred to the physical location of theWTRU with respect to the CSG cell.

In a UMTS intra-frequency scenario, the WTRU may not need gaps to readthe SI of the HNB. In UMTS inter-frequency and LTE intra- andinter-frequency scenarios, the WTRU may use autonomous gaps or scheduledgaps to read the SI of the HNB. Idle periods during discontinuousreception (DRX) may be used provided that available and autonomous gapsmay be controlled by the eNB. In a UMTS intra-frequency scenario, aspart of measurement configuration, the network may configure a range ofPSCs for which the WTRU may perform access checks and report additionalinformation when reporting measurements.

In the current state of the HNB specifications, CSG IDs may be added tothe WTRU's allowed list by manual selection in idle mode and successfulregistration. However, the WTRU may not handover in connected mode to aHNB with an ID that is not part of its white list, unless there is anongoing emergency call. For example, if the user enters a coffee shopfor the first time during a connection, the WTRU may not be allowed tohandover to the HNB belonging to the coffee shop. It may have to waituntil the connection is over to register in the idle mode. In somecases, such as, internet browsing, the user remains in connected modefor a long period of time and does not wish to interrupt the currentconnection for registering with the network to access a HNB the user hasnot previously visited.

Additionally, if the WTRU is in idle mode, an autonomous search functionmay not be performed in the WTRU if the CSG white list is empty. If theCSG identity of the target cell does not match any of the CSGs in thewhite list, the WTRU does not attempt to perform cell reselection.

When manual search or autonomous search is referred to herein, itimplies that the search is only targeted to a HNB, meaning thatautonomous search is equivalent to autonomous search for HNB and manualsearch is equivalent to manual search for HNB.

Manual and autonomous searches are described as being performed whilethe WTRU is in connected mode and are performed for finding new HNBs,meaning HNBs for which CSG IDs are not part of the WTRU white list.

The expression ‘signaled to the WTRU’ indicates that the network sendsconfiguration parameters to the WTRU by means of an existing radioresource control (RRC) or non-access stratum (NAS) message or by meansof a new RRC or NAS message. For example, in the existing RRC messagecase, the message may be a measurement control message in UMTS or anRRCConnectionReconfiguration message in LTE.

A number of procedures allow the WTRU to search and add one or more CSGIDs to the WTRU white list while in connected mode (or optionally, inidle mode as well). Such procedures include but are not limited to WTRUautonomous search or a manual search, WTRU-initiated procedures, ornetwork-initiated procedures. Additionally, methods that allow thenetwork and/or the NAS to add CSG IDs are also described.

When referred to hereafter, idle mode may refer to idle mode in LTEsystems and/or to idle mode, CELL_PCH, URA_PCH, or CELL_FACH mode. Inother words, in LTE connected mode and in UMTS cell_DCH, change ofserving cell is performed through handover while in LTE idle mode and inUMTS idle, cell_PCH, ura_PCH and cell_FACH modes, change of cell isperformed through cell reselection.

FIG. 6 illustrates a flow diagram of a procedure 600 for searching andadding CSG IDs to a white list while in a connected mode. An autonomoussearch of a CSG cell in connected mode is enabled in the WTRU at 605.Either a WTRU initiated trigger or network initiated trigger eventsoccurs for starting the autonomous search of neighboring CSG cells andis validated at 610. The WTRU initiated triggers and the networkinitiated triggers are described hereafter. The WTRU is configured tosend a message to the network indicating the start of an autonomous CSGcell search in the connected mode at 615. The network is configured tosend a message to the WTRU to request the WTRU to detect, measure, andreport neighboring CSG cells at 620. The WTRU starts detecting andmeasuring CSG cells at 625. The WTRU sends a message to the networkincluding a PSC of CSG cells and measurements at 630. The WTRUautonomously starts reading SI of the best CSG cell, or the networkindicates to the WTRU the CSG cell for which CSG cells it may acquirethe SI at 635. The WTRU sends a NAS message to request the network tobecome a member of the new CSG ID at 640. The WTRU determines whetherthe network responds with acceptance or rejection at 645. On a conditionthat the WTRU receives response with acceptance, the WTRU handovers tothe CSG cell at 650. The WTRU adds the new CSG ID to the white list at655. On a condition that the network answers with a rejection, thenetwork uses a new reject cause to indicate the rejection to the WTRU at660.

Each of the actions described in FIG. 6 are described in more detailhereinafter. The triggers to initiate a HNB search include, but are notlimited to, WTRU initiated and network initiated triggers.

In a WTRU initiated scenario, the WTRU may autonomously initiate thesearch for neighboring HNBs or the WTRU may initiate a report to thenetwork to indicate a need or desire for measurement, as described in605. To allow the WTRU to start measuring and/or detecting other HNBs, anumber of procedures and solutions are described. The proceduresdescribed herein allow the WTRU to extend the search procedures tomeasure and/or detect and connect to a previously unvisited HNB or to aCSG having an ID that was not previously in the WTRU's CSG white list.

To efficiently allow the WTRU to limit excessive HNB searches, batteryconsumption, and disruptions to current connections, the WTRU mayinitiate the procedure as a result of one or a combination of thefollowing triggers at 610. These triggers may also be initiated by thenetwork at 610, which serve merely as examples and is not an exhaustivelist.

One of the triggers may be that the WTRU is not already connected to aHNB. For example, the WTRU is connected to a macro cell or the signalquality of the current serving cell goes below a predefined threshold.Optionally, the signal quality must remain below the threshold for aconfigured period of time to trigger. This threshold may be determinedby the WTRU or signaled by the network.

Another trigger may be that the signal quality of the current frequencygoes below a predefined threshold. Optionally, the signal quality mustremain below the threshold for a configured period of time to trigger.This threshold may be determined by the WTRU or signaled by the network.

The priority level, for the current CSG on which the WTRU is on, haschanged. Alternatively, the WTRU is determined to be in a low mobilitystate. For example, if the WTRU mobility is low, it may be assumed thatthe user is indoors where a HNB may be available. Examples of locationswith low WTRU mobility include private homes, airports, coffee shops,enterprises, and the like.

Another trigger may be that the user activity becomes such that the datarate available on the current serving cell is no longer sufficient. Forexample, if the serving cell is a macro cell, it is possible that theuser may get a better data rate on a HNB.

Another trigger may occur when the white list of the WTRU is empty. Thismay imply that the WTRU is a HNB-capable WTRU with a potentialsubscription that has been unable to register with the CSG cell. Thismay allow the WTRU to attempt to add a new CSG ID in its white list.Additionally, the default or configured time may have elapsed and theWTRU may not have attempted registration on a HNB with a matching ID orthe WTRU may not have detected any CSG with the same ID. For example,this may be due to the addition of a CSG ID in a roaming area which hasbeen left by the WTRU and the CSG ID is still in its white list.Alternatively, a trigger may occur when there are no HNB fingerprintsstored in the WTRU.

The user enters an area in which there is a high probability of apresence of a HNB and for which the WTRU does not have any HNBfingerprint stored. The probability of HNB presence may be determined bythe network depending on the WTRU's approximate location (e.g., based ona GPS or on a macro cell's neighbor list) and signaled to the WTRU. TheWTRU may optionally store a list of areas where HNBs are available usingthe network indications or via a pre-configured list. For example, thismay be signaled over the macro cell to the WTRU. A broadcast ordedicated RRC indication may be used to notify HNB-cap able WTRUs thatthe current area may potentially contain HNBs with which the WTRU mayconnect temporarily. Also, this may be implied if there are changes tothe services available in the current cell or current tracking area,routing area, and the like. For example, if the WTRU is informed thatthere is availability of services such as selected Internet protocol(IP) traffic offload (SIPTO) (or other types of services, such as, localIP access (LIPA)) via NAS signaling routing area update accept, or anyother method, the WTRU may assume the availability of HNBs.

The autonomous search may be triggered periodically, with a perioddetermined by the WTRU or signaled by the network and which mayoptionally depend on the type of location the WTRU is in. For example,in an urban area the timer duration may be shorter than in a rural area.

A manual search is triggered by the user while the WTRU is in connectedmode. Alternatively, a trigger may be when an amount of time has elapsedsince the last time the WTRU attempted to connect/register to a HNB inthe area.

Another trigger may be when upon power on or re-registration to thenetwork, regardless of whether the WTRU's white list is empty, or uponselection of a new public land mobile network (PLMN), or after aninter-PLMN handover. Alternatively, when the WTRU detects a hybrid CSGcell or enters an area for which it knows it had previously detected orconnected to a hybrid cell, a trigger may occur.

Additionally, the autonomous search may only be triggered in the casethat the WTRU is not in the fingerprint area of a HNB for which the CSGis in the WTRU's white list. This is because it may be preferable tosearch for the previously visited HNB rather than to add a new CSG ID tothe white list. The user may still force a manual search if the user isinterested in handing over to a new HNB instead of a previously visitedHNB.

To limit the number of HNB searches in connected mode, the network mayrestrict the WTRU to only use the manual search triggered by the userand disable the autonomous search initiated by the WTRU without user'sinteraction. Additionally, allowing the autonomous search may be anoption configurable by the user of the WTRU.

Further, the network may initiate or trigger the WTRU to startmeasurements/detection of HNBs at 610. This may be done by an explicitindication from the network to the WTRU to initiate measurements or bytriggering the WTRU to start autonomous search and measurements of HNBseven if the white list is empty. This may be done, for example, via adedicated RRC message or via a broadcast, advertisement, orimplementation. These solutions may be applicable to both connected andidle mode mobility.

In one example, the initiation of the procedures may be done viaexplicit dedicated signaling to the WTRU. In another example, thenetwork may send the information to all WTRUs connected to a macro cell.

Either of the examples may be performed as a result of reception of anindication from the WTRU that certain services or mode of operation havebeen enabled. For example, based on user interaction, the WTRU's mode ofoperation may be changed such that SIPTO/LIPA services or other servicesare desired. This may trigger an indication, for example, a SIPTO/LIPAcapability enabled indication, to the network which then requests theWTRU to start detection/measurements.

While the WTRU is under the coverage of a macro cell in connected mode,the network may use the commercial mobile alert system (CMAS) or anyother broadcast feature to advertise the existence of one or multiplepublic, private, or hybrid CSG cells. The network advertizes HNBs bysending one or any combination of the parameters, such as, CSG IDs,PCI/PSC range or list, frequencies, CSG dedicated frequencies, RATs, ora CSG presence indication (1 bit). This information may be broadcastedto the WTRU via the macro cell or sent to the WTRU via multicastservices such as multimedia and broadcast multicast services (MBMS).

Based on the WTRU reported/known capabilities, the network may decide tosend a dedicated message to a WTRU or group of WTRUs indicating thepresence of the HNBs containing one or any combination of the aboveparameters. The dedicated message may be transmitted to the WTRU via anRRC reconfiguration message or a measurement control message.

Upon reception and decoding of the message, the WTRU in connected modemay decide based on an algorithm to use or start its autonomous searchif allowed at 625, or manual search based on user decision to search forthe HNBs using its search capabilities on different frequencies or RATs.The actions associated upon these indications are described in moredetail below.

If the network signals only the CSG presence indication, then the WTRUmay, in addition to this indication, use any of the procedures definedabove. Provided one of the above mentioned conditions or triggers aremet and the WTRU may begin searching autonomously.

Additionally, as another HNB search trigger, depending on theinformation sent by the network, WTRU capabilities, and internalsettings, the WTRU may notify the user and request user's permission tostart manual search according to HNB presence. The user may also chooseto stop the autonomous search function under these conditions.

Provided the WTRU fails to find any PCI/PSC for defined timer duration,the WTRU may autonomously stop looking for HNBs. The timer may benetwork signaled, user defined, or a WTRU internal per PSC/PCI definedtimer. The WTRU may periodically notify the user about the searchprogress, so that the user may manually cancel the procedure. The WTRUmay stop searching after detecting one or a group of PCI/PSC beinglimited by a counter that may be user, network, or internally defined.The WTRU may stop the HNB PCI/PSC search after a defined number ofretries on all or a limited number of frequencies or bands based on itscapabilities.

Provided one or a combination of the above mentioned conditions/triggersis met, the WTRU may autonomously initiate a HNB search procedure. Oneor a combination of the following actions upon triggering of a HNBsearch may be performed. The WTRU may scan all frequencies in thesupported bands. The WTRU may only scan CSG dedicated frequencies ifavailable or if provided to the WTRU. The WTRU may scan only a subset offrequencies designated for HNB search in connected mode. If no PSC/PCICSG split is provided to the WTRU at the point at which autonomoussearch is initiated, the WTRU may measure and report all detectedPSC/PCIs on the frequency it is scanning. If a PSC/PCI range is providedto the WTRU, the WTRU may detect the PSC/PCIs that are part of the CSGPSC/PCI split, measure, and, optionally, report them in the newfrequency at 625.

The WTRU may, optionally, indicate to the network that the reportedPSC/PCI is an unvisited PSC/PCI. This indication may be used by thenetwork to determine whether it should explicitly signal to the WTRU toread the SI of the cell.

Given that a PSC/PCI confusion may exist, the WTRU may also need toacquire the SI of HNBs. For the intra-frequency case, the WTRU may havealready detected and measured the PSC/PCI corresponding to the HNB inthe vicinity but may not have measured the SI. Therefore, the WTRU mayinitiate an autonomous SI reading on the same frequency provided one ofthe above triggers has occurred. The WTRU may choose to autonomouslyacquire the SIs for highest ranked or best quality cells at 635. Oncethe SIs are read, the WTRU may send a measurement report to the networkwith all of the PSC/PCI and SI information for each.

Also, the WTRU may read the SI of a HNB, according to user selection.This may be achieved by displaying the set of provided HNB names (e.g.,via broadcast or dedicated messages) to the user, provided that thesignal quality of the displayed HNB is above a threshold and allowingthe user to make a selection. The user may either make a selection ofthe HNB to attempt to connect to, provided it has the list of the nameand PSC/PCI associated, or the user may trigger a manual search inresponse to the message. The user may also trigger an autonomous SIacquisition of the neighboring cell.

For idle mode WTRUs, the WTRU may chose to reselect to the best cell orthe highest ranked cell in that frequency, even if the CSG ID does notmatch any of the CSGs in the white list. This may, optionally, be doneonly if the WTRU is in a low activity mode and if one of the triggersdefined above is met. The autonomous SI reading may also be triggeredfor the inter-frequency search case provided one of the conditions aboveis met.

Upon reading the SI and acquiring the cell identity, HNB name, CSG, andthe like, the WTRU may perform one or a combination of the following.The WTRU may report this information to the network. The WTRU mayreselect to the best cell in the detected/measured set even if the CSGID is not in the white list. The WTRU may display the set of providedHNB names (e.g., via broadcast or dedicated messages) to the userprovided that the signal quality of the displayed HNB is above athreshold and allow the user to make a selection.

In idle mode, for example, the WTRU may choose to read the SI of thetarget CSG cell (e.g., the highest ranked cell) while still being campedon the source cell. The WTRU may read the SI, and if no CSG match isdetected, it may display the name of the HNB to the user and ask if theuser wants to connect to this HNB. Depending on the user's knowledge ofrecent subscriptions and if the user chooses to attempt to add thiscell, the WTRU may trigger a cell reselection to the target CSG cell.Also, the WTRU may send an indication to the network to add the CSG IDto the white list via the source cell, using an RRC message. Forexample, this may be performed via a CELL_UPDATE message where the WTRUappends the CSG ID of the target cell that is not on the white list. Anew cause for cell update may be introduced (e.g., CSG addition) or anRRC connection request message may be used. Also, it may trigger a NASlevel message or a dedicated RRC message.

Upon selection of a cell to add to the white list, the WTRU in connectedmode may send a report to the network. It may report all cells detectedor measured, a subset of the measured cells fulfilling a set ofcriteria, or the selected cell. The report may contain the signalquality of the cell, the CSG ID, the cell identity, and optionally anindication that the WTRU wishes to attempt to add this CSG to its whitelist, even if it is a non-member. This may be done via a one bitindication to the network, or by falsely indicating that the CSG is amember. Provided the CSG ID access check is performed on the networkside and fails, it may mean that the WTRU should not add this cell tothe white list. If it passes in the MME, for example, that indicatesthat the WTRU is allowed on the CSG.

Also, the WTRU may use the likely indication bit together with theprovided SI information to report to the network that it wishes toattempt to be added.

In an alternate embodiment, the WTRU does not perform autonomousdetection and/or measurements of the SI. The WTRU may send an indicationto the network that it wishes to perform a CSG search/detection/SImeasurement even though it does not believe it is in the vicinity of avisited CSG cell (e.g., in its fingerprint). This may be in the form ofone or more bits added to the proximity indication message or a newmessage/event added for this purpose. This bit may provide manual searchtriggered, periodic search triggered, CSG white list empty, CSG whitelist empty but user believes it has a subscription, or user desires tomeasure CSGs even if not in fingerprint. The network may then configurethe WTRU to take measurements and report the measurements to the networkaccordingly.

If the WTRU detects PCI/PSC having a reasonable signal quality (i.e.,better than a predefined threshold), the WTRU may follow the procedureslisted herein and the procedures for updating the white list andfingerprint, before finally performing the handover procedure.

Updating the white list in connected mode and handover procedure are nowdescribed. Provided one of the triggers (i.e., WTRU-initiated ornetwork-initiated) above is met (i.e., once the WTRU has acquired theCSG ID of the CSG cell), the WTRU may attempt to connect to a CSG celleven if this CSG does not match any of the CSGs in the WTRUs white list.Described below are embodiments which allow the WTRU to connect to sucha cell and embodiments which allow the WTRU to update the white list.

In a first embodiment, once the CSG ID has been read by the WTRU in theSI broadcasted by the HNB, the WTRU may send a location registrationrequest for the HNB to the network. The location registration requestmay be sent via an uplink direct transfer in UMTS, anULInformationTransfer in LTE, any other existing RRC message, or a newmessage, including the CSG ID in the request and, optionally, thePSC/PCI and/or the cell identity, CGI for LTE, of the HNB.

Although the procedure in the first embodiment is not performed from theCSG cell itself, the WTRU, by sending this message, performs a locationupdate as if it is on the CSG cell but without interrupting any ongoingcall/session. The location/routing/tracking area update messages have anew update type to indicate that this is for an attempt to access a CSGcell. Moreover, the WTRU may include the CSG ID with respect to whichthe update is performed. Thus, based on the subscriptioninformation/status in the network, the location/routing/tracking areaupdate procedure may be accepted or rejected at 645.

If accepted, a new update result may be used in the accept message thatis sent to the WTRU. Moreover, the network may include the CSG ID thatit received in the request message. This may allow the WTRU and thenetwork to be sure that the same CSG ID is being referred to 650. TheWTRU may then add the ID to its white list and assume that access to thenetwork from that CSG cell may be granted at 655. In addition, the WTRUmay first access the cell and then initiate thelocation/routing/tracking area update procedure on that cell. The WTRUmay then add CSG ID to the list once the location update is accepted.The latter location update may follow normal procedures and updatetypes. Also, the WTRU may add the CSG ID to its whitelist and stillperform a location/routing/tracking area update provided that it ishanded over to the CSG cell.

If the location update is rejected due to an invalid/expiredsubscription for the WTRU at 645, the network may use a new rejectioncause to indicate this to the WTRU at 660. In this case, the WTRU maynot consider the location/routing/tracking area as invalid and may notadd the location/routing/tracking identity to the list of forbidden areaidentities.

The WTRU may also be informed whether handover may still be performedwithout adding the CSG ID to its white list, for example, if the CSG isoperating in hybrid mode.

Upon success of the location registration procedure, if the network sentback a location registration accept to the WTRU, the WTRU may add thenew CSG ID to its white list and start the handover procedure to thisHNB. The fingerprint of the HNB (i.e., location information) may also bestored by the WTRU at the same time it adds the CSG ID to the white listor the fingerprint may be added after successful handover to the HNB.This ensures that the access check performed by the network is verifiedfirst and that the WTRU does not store an erroneous fingerprint.

In addition to sending an update message, a new NAS message may bedefined to generically provide subscription/status information for otherreasons (e.g., whether SIPTO/LIPA, non-packet-switched (PS) servicessuch as short message service (SMS) may be provided from a specificcell) including CSG access. The WTRU may include information such as theservices for which it is seeking status information about, for example,CSG access. Based on the response of the network, the WTRU may takefurther actions such as adding the CSG ID to its white list andattempting handover to that cell.

In a second embodiment, the WTRU may try to connect to the target celleven if the CSG ID does not match. In idle mode, the WTRU may performcell reselection to the cell. If the cell reselection is successfullycompleted and the WTRU is not rejected, the WTRU may add the CSG ID tothe CSG white list. An exception to this rule may apply provided that anemergency call has been initiated.

In connected mode, the WTRU may send a measurement report indicatingthat the CSG cell is a non member or send a measurement report with thePCI/PSC measured and the signal quality of the cell using existingsignaling or any new signaling procedures. Provided that a handovercommand is sent in return to the WTRU indicating that the handovershould be performed to the target CSG cell, the WTRU may add the CSG IDto the CSG white list.

Therefore, the RRC layer or the access stratum (AS) may update the CSGwhite list or send the indication to the NAS to add the CSG. If the WTRUhad not read the SI of the cell (e.g., if PSC/PCI confusion exists, thenetwork may not ask the WTRU to read the SI of the cell), the WTRU mayperform one or a combination of the following to obtain the CSG ID ofthe cell. The WTRU may perform the handover and then acquire the SI ofthe cell to obtain the CSG ID. Once the CSG ID is obtained, it may addit to the white list. The network explicitly indicates the CSG ID of thetarget cell to the WTRU in the handover message and whether it can beadded to the white list or treated as a hybrid cell.

The WTRU may also optionally update its fingerprint information as well.Also, the WTRU may perform the handover or cell reselection, yet notautonomously add the CSG ID to the CSG white list. The WTRU may send anindication to the network indicating that the CSG ID of the cell that itis currently connected to is not in the CSG white list. The network maythen explicitly update the CSG white list using higher layer signaling.

In another embodiment, once the network detects that the WTRU isattempting to connect to a CSG cell that is not in the white list, thenetwork may send a RRC connection reject to the WTRU. This may allow theWTRU to fall back to idle mode and initiate a manual search. Optionally,a new cause may be added to the RRC connection reject that indicates tothe WTRU that it may attempt to connect to the CSG and begin performinga location area update or routing/tracking area update.

If the network does not answer the location registration request fromthe WTRU, the WTRU sends back a location registration reject, or theWTRU does not perform the handover or is not allowed to reselect to thecell as in the previous embodiments. The network may not answer therequest from the WTRU if a timer expires in the WTRU before the locationregistration accept is received. And, the location registration rejectmay occur, for example, if the WTRU is not allowed to access the HNB.The WTRU may not add the CSG ID to its white list and may optionally addthis CSG ID to a black list. It may also add the correspondingfingerprint to the black list so that it does not try to add this CSG IDto its white list again and/or does not trigger an autonomous search forthis cell. An entry in the black list may be valid for a certain periodof time to take into account the changes in time of the HNB accessauthorizations and to allow the WTRU to attempt to add a previouslyblacklisted HNB in a future period.

After an unsuccessful attempt, the WTRU may try to measure another oneof the HNB PSC/PCI, it had detected during the autonomous and manualsearch. If the HNB PSC/PCI is above a predefined threshold, the WTRU mayperform another location registration procedure after a reading of theCSG ID in the SI. The WTRU may also avoid measuring the HNB again andreuse the signal quality of the HNB stored during the autonomous ormanual search to verify that it is above a predefined threshold.

A message may be sent to the user to request the user to initiate manualsearch. The user may then choose to initiate the measurements, if it isaware that it has subscribed to any of the HNBs. If the advertised CSGsor HNB are not in the WTRU's white list, the WTRU may trigger anautonomous search of CSG cells procedure (i.e., 605-660 in FIG. 6),thereby allowing it to connect and add the CSG ID to its white list.

If the network does not allow the HNB registration in connected mode,the WTRU may keep the information until the end of the call. The WTRUmay then enter idle mode and register with the HNB cell. If theregistration is successful, then the WTRU may update its white listaccordingly.

Additionally, the WTRU may notify the user of the failure of the HNBregistration in connected mode, so that the user may choose to stop thecall on macro cell and manually trigger the registration with thedetected HNB.

The capabilities of signaling of WTRU and the network are now described.Not all WTRUs may be capable of adding a new CSG ID to their white listwhile in connected mode. This capability may be indicated to the networkvia an existing RRC message, such as the RRC connection request, byadding an information element (IE) (a one bit IE may be sufficient) orvia a new message. Also, the WTRU may include the indication in the MSnetwork capability IE that is sent during registration.

Additionally, not all networks may be capable of performing a locationregistration on a HNB while a WTRU is in connected mode. This networkcapability may be explicitly signaled by the network to the WTRU withone or a combination of the following implementations.

A new IE may be added in the RRC connection setup or in any otherexisting RRC message. A new message sent by the network to the WTRU maybe defined. A new optional IE may be added in the NAS messagesincluding, but not limited to, a location registration accept/rejectmessage and used by the network provided the WTRU sends a locationregistration request on a HNB to the network, possibly while inconnected mode.

Further, this network capability may be determined implicitly by theWTRU with one or a combination of the following WTRU implementations.After a certain number of location registration requests sent by theWTRU in connected mode for a HNB for which the WTRU receives a locationregistration reject or after no response at all, the WTRU may determinethat the network does not support the capability and may stop sendingthis type of requests. After any other NAS/RRC message is sent to thenetwork requesting the outcome of registration on a particular CSG cellwith no response having been received for a given period of time or fora certain number of tries. After a certain number of gap requests sentby the WTRU to the network for detecting, measuring, or reading the SIare not granted by the network, the WTRU may determine that the networkdoes not support the capability. The gap requests may refer toauthorization to use idle periods in the case of DRX, autonomous gaps,or requests for scheduled gaps.

While in idle or connected mode, the WTRU camped on a UTRAN or anEvolved-UTRAN (E-UTRAN) cell already has a context-ID and an existingRRC connection. Therefore, sending a location update may trigger alogical error due to the receiver state, and eventually cause an updateof the context-ID.

The following procedures apply to both WTRU idle and connected modes inboth UTRAN and E-UTRAN and are aimed to resolve any system logicalerrors.

In the network capability signaling, the network (i.e., UTRAN orE-UTRAN) may signal the support for the CSG ID background access checkin connected and/or idle mode in a SI block sent as the broadcastcontrol channel, paging, or any other existing or new RRC message.

In the UTRAN procedures, after measuring the new CSG/hybrid cell, theWTRU may send a location update, any other existing RRC message, or anew message for the HNB to the network via an uplink direct transfer. Ifa location update message is used, a special flag may be used toindicate a target CSG ID background access check. If an existing RRC ora new message is used, the flag may be required to inform the HNB aboutwhich of the network capability signaling procedure, UTRAN caseprocedure or E-UTRAN case procedure to follow.

Upon receiving this message, the HNB may use the WTRU registrationrequest message, indicating the new cause target CSG ID backgroundaccess check to send to the HNB-GateWay (GW). The HNB-GW may beresponsible for the WTRU access check procedure. The access check mayalternatively be done by the mobile switching center (MSC) or theserving general packet radio service (GPRS) support node (SGSN). Thismessage may contain the following information: WTRU ID, WTRUcapabilities, registration cause such as CSG ID background access check,target access check CSG ID, and target access check Cell ID. Also, theWTRU may decide to send a list of multiple measured target access checkCSG ID and target access check Cell ID grouped elements.

Upon receiving the WTRU registration request from the HNB with CSG IDbackground access check cause, the HNB-GW with the above information maybe able to perform the target HNB access verification and reply with aWTRU register accept message that will contain the actual context ID ofthe WTRU as well as the CSG ID.

Additionally, if the HNB-GW does not have a CSG ID that the WTRUrequested for background access check in its database, the HNB-GW mayreply with a WTRU register reject message, or it may send a message tothe HNB management system or core network to resolve the access check.If the access check performed by the HNB-GW returns a negative result, aWTRU register reject message containing the CSG ID may be issued.

If multiple CSG IDs are targeted, the HNB-GW may send a list of allowedCSGs in the WTRU register accept message. If none of the inquired CSGIDs are allowed, it may send the WTRU register reject message with alist of non-allowed CSG IDs. The HNB may send a location update acceptor reject based on the received answer from HNB-GW, transferring theentire answer. The WTRU may add to its white list the positivelyverified access CSG IDs.

For the E-UTRAN procedures in LTE, the CSG access check is performed atthe MME level. The HNB-GW has a role of S1 interface concentrator andcontrol as well as user planes multiplexing role. The WTRU may use aULInformationTransfer. The CSG ID background access check may berequired, followed by a list of measured CSG ID and global cell IDparameters.

The ULInformationTransfer message is transparent to the HNB or eNB.However the HNB or eNB may append the cell ID to the message. Thismessage may arrive at the MME over S1 interface encapsulated in theuplink (UL) NAS transport message.

The MME may process the request based on a special procedure involvingthe following elements that the WTRU may provide in the message: WTRUID, WTRU capabilities, cause such as CSG ID background access check,target access check CSG ID, and/or target access check Cell ID.

There may be multiple pairs of CSG ID and Global cell IDs that the WTRUmeasured. After verifying the access, the MME may reply using a downlink(DL) NAS transport message with the allowed/not allowed CSG list. TheHeNB may use the DL information transfer message to convey the CSG IDbackground access results encapsulated by the DL NAS transport message.Upon reception of the DL information transfer message, the WTRU mayupdate its white list accordingly, for example, by adding or removingCSG IDs based on information received.

If the MME does not have in its database the specific CSG access list,it may inquire about the target MME based on the tracking area identityand reply based on the returned message. Also, if the MME does not haveknowledge of the CSG access list, it may simply reject the access for aparticular CSG ID.

In another embodiment, a method and apparatus are disclosed for cellidentity validation failure in handover.

Situations may arise that require a handover of the WTRU from the sourceHeNB to the other HeNB or cell, which may be referred to as the targetcell. The target cell may be a CSG cell, which may include a CSG HeNB ora close mode cell. A CSG cell may be a macro cell. A target CSG cell,which may be a CSG HeNB or CSG macro cell, may need to validate a CSG IDof the WTRU to determine if the WTRU is a member of the CSG that mayconnect with the target CSG cell. The WTRU may transmit its CSG ID tothe source HeNB, which may transmit the WTRU CSG ID to the target CSGcell. The target CSG cell may compare the received CSG ID from thesource HeNB with a CSG ID that the target CSG cell is currentlybroadcasting. The target CSG cell may not accept the transfer if the CSGID received from the source HeNB is different than the CSG ID beingbroadcast by the target CSG cell as the validation of the WTRUmembership in the CSG would have failed. The attempted handover may alsofail as a consequence.

In another embodiment, the source HeNB may transmit the WTRU CSG ID tothe MME. The MME may use the WTRU CSG ID to determine if the WTRU is amember of the CSG that may connect with the target CSG cell. The MME maytransmit both the WTRU CSG ID and the membership status of the WTRU tothe target cell. The target CSG cell may reject the transfer of the WTRUas the membership status validation would have failed and the attemptedhandover may fail as a consequence.

Among the reasons that the validation may fail at the target CSG cell,one may be if the MME and the target CSG cell are out of synchronizationregarding the CSG ID being broadcast by the target CSG cell. Forexample, the target CSG cell may have a different configuration at thetime the MME determines if the WTRU is a member of the target CSG cell'sCSG. However, a WTRU reporting a CSG ID for which validation has failedmay still be member of the actual CSG ID reported by the target CSGcell.

In an embodiment, when a handover may fail due to a CSG ID mismatch atthe target CSG cell, the MME may be informed of the actual CSG IDbroadcast by the target CSG cell rejecting the handover. The source MMEmay update the WTRU membership in the source HeNB and a new attempt tohandover using the correct CSG ID may be made.

The embodiments contemplate CSG ID-CGI validation that may focus onsynchronizing CSG ID-CGI information within wireless communicationnetwork elements inter operating in a network supporting (e)NBs andHeNBs. As indicated previously, should a hybrid cell detect that the CSGID provided in a handover request may be different than the one thehybrid cell is broadcasting, the hybrid HeNB may still accept thehandover request. Alternatively, should the target cell be a CSG cell,the target CSG cell may reject the handover request and the target CSGcell may send back a handover failure message indicating an invalid CSGID in the cause IE. In an embodiment, the target CSG cell may alsoinclude in either the handover failure or the handover request ACKmessages the value of the valid CSG ID broadcasted by the target CSGcell so that the network may be synchronized in this regard.

In an embodiment, where the target cell may be a hybrid cell, the hybridcell may accept a handover request, albeit treating the WTRU as anon-member. Should the WTRU be a member of the new CSG ID broadcast bythe target hybrid cell, the MME may update the WTRU membership statusthrough a WTRU context modification message and therefore allow thetarget hybrid cell to treat the WTRU as a member.

In another embodiment, when the target cell is a CSG cell, and uponreceipt of a handover preparation failure indicating a current or validCSG ID broadcasted by the target CSG cell, the MME may perform a new orupdated access check to determine the WTRU membership status. The MMEmay query an HSS database to determine the membership status of the WTRUin light of the current CSG cell ID. Alternatively, the MME maydetermine the WTRU membership status based on information stored on theMME. This updated access check may provide the new/current membershipstatus (member or non-member) to the source HeNB in the handoverprepallation failure message along with the correct target CSG ID.

Referring to FIG. 7, the MME may determine a status of a mobile device,(i.e., or WTRU), relative to a first network node such as the target CSGcell at 705. The MME may update a second network node, such as thesource HeNB with a current identification of the first network node uponfailure of a first transfer of the WTRU from the source HeNB to thetarget CSG cell at 710. On a condition that the first transfer was notsuccessful, the MME may initiate a second transfer of the WTRU from thesource HeNB to the target CSG cell at 720. The initiation may be basedat least in part on the failure of the first transfer and the status ofthe mobile device or WTRU. The MME may update the source HNB with acurrent identification of the target cell at 715, on a condition thatthe first transfer was a failure.

In another embodiment in which the target cell is a target CSG cell, thetarget CSG cell may be in communication with a different MME than theMME with which the source HeNB may in communication. This may bereferred to as inter-MME. The MME in communication with the target CSGCell may be referred to as the target MME. The MME in communication withthe source HeNB may be referred to as the source MME. The source MME maycommunicate with the target CSG cell and the target MME may communicatewith the source HeNB. In such an embodiment, when the handoverpreparation failure may be received indicating current (i.e., valid) CSGID broadcast by the target CSG Cell, the target MME may perform a new orupdated access check to determine WTRU membership status (i.e., memberor non-member). If the WTRU is a member, the target MME may re-issue ahandover request toward the target CSG cell that may include the new CSGID and the membership status. The target MME may know the target CSGcell identified by the source HeNB for the handover based on theinformation provided in the previous handover request. This embodimentmay be considered to be a by-pass of the source HeNB as the target MMEis not acting through the source HeNB to re-issue the handover request.

Upon receiving a successful handover response (i.e., handover requestACK) from the target CSG cell, the target MME may notify, via a forwardrelocation response, the source MME of the new CSG ID and the membershipstatus. The source MME may then inform the source HeNB of the new CSG IDand the WTRU membership status using a handover command. In anembodiment in which one MME may be in communication with both the targetCSG cell and the source HeNB, the MME may function as the source MME andthe target MME.

Also, should the re-issued handover request with the new CSG ID resultin a failure, upon receiving an unsuccessful handover response via ahandover failure message, from the target CSG cell, the target MME maynotify the source MME that the handover request has failed for both theprevious and new CSG IDS using a forward relocation response-reject. Thenotification may include the new CSG ID as well as the WTRU membershipstatus.

In another embodiment in which the target cell is a CSG cell, the sourceMME may perform a new or updated access check to determine WTRUmembership status (i.e., member or non-member). If the WTRU is member,the source MME may re-issue a handover request toward the target CSGcell that may include the new CSG ID and the membership status.

Upon receiving a successful handover response (i.e., handover requestACK) from the target CSG cell, the target MME may notify the source MMEof the new CSG ID and the membership status using a forward relocationresponse. The source MME may then inform the source HeNB of the new CSGID and the WTRU membership status using a handover command.

Should the re-issued handover request with the new CSG ID result in afailure, upon receiving an unsuccessful handover response using ahandover failure, from the target CSG cell, the target MME may notify bya forward relocation response-reject, the source MME that the handoverrequest has failed for both the previous and new CSG IDS and include thenew CSG ID as well as the WTRU membership status. This embodiment may beconsidered to be a by-pass of the target MME as the source MME is notacting through the target MME to re-issue the handover request.

In another embodiment, in which the target cell may be a CSG cell andmay not be a target MME, the source MME may perform a new or updatedaccess check to determine WTRU membership status (i.e., member ornon-member). If the WTRU is member, the source MME may re-issue ahandover request toward the target CSG cell that may include the new CSGID and the membership status.

Upon receiving a successful handover response (i.e., handover requestACK) from the target CSG cell, the source MME may inform the source HeNBof the new CSG ID and the WTRU membership status using a handovercommand.

Also, should the re-issued handover request with the new CSG ID resultin a failure, upon receiving an unsuccessful handover response from thetarget CSG cell, the source MME may notified of the handover request hasfailed for both the previous and new CSG IDS and the notification mayinclude the new CSG ID as well as the WTRU membership status using ahandover failure.

In another embodiment, in which the target cell is a CSG cell, a HNB-GWmay perform the access check and re-initiate the handover toward thetarget CSG cell. For example, this may be in the case of 3G/UTRANintra-HNB-GW handover scenario. In other embodiments, the functionsdescribed as performed by the one or more MME may be performed by aHNB-GW node, a SGSN node, a GW node, or a MSC node, for example.

In an embodiment in which the target cell is a CSG cell, the source HeNBmay receive a handover preparation failure that indicates the current(i.e., valid) CSG ID broadcasted by the target CSG cell. Also, thesource HeNB may receive an indication that the MME has determined thatthe WTRU may be a member of the target CSG cell's CSG. The source HeNBmay, in one embodiment, re-attempt the handover. In another embodiment,the re-attempt of the handover may occur after requesting a new set ofmeasurements, which may require the WTRU to read the correct SI.Measurements may include signal attributes that are useful in making ahandover decision, such as but not limited to pilot or reference signalstrength and/or quality.

In another embodiment, the source HeNB may request the WTRU to read theSI to ensure that the correct CSG ID pair is provided in subsequentproximity indications (e.g., without commanding a new handover).

In another embodiment, the source HeNB may issue a handover command, viaa handover required/forward relocation request, toward the target CSGcell for which the correct CSG ID has been received. In anotherembodiment, the source HeNB may issue a handover command using anRRCConnectionReconfiguration that may include the new CSG ID. Forexample, as part of the mobilityControlInfo IE, so that the WTRU maymodify its own mapping.

In another embodiment, the source HeNB, upon receipt of a handoverrequest ACK message indicating a success, may issue a handover commandusing an RRCConnectionReconfiguration toward the WTRU. The handovercommand may include the new CSG ID and an updated member status (e.g.,as part of the mobilityControlInfo IE), so that the WTRU may modify itsown mapping and/or update its allowed CSG list. For example and forpurposes of clarity, a successful handover may occur where the initialWTRU CSG ID is validated by the target CSG cell, where the MMEsuccessfully requests the target CSG cell to accept the transfer withthe new (i.e., validated) CSG ID, or where the source HeNB initiates asuccessful handover with the new (i.e., validated) CSG ID.

Referring to FIG. 8, the source HeNB may receive an indication of afailed first transfer of the WTRU from the source HeNB to the target CSGcell at 805. The source HeNB may receive a current identification (i.e.,valid or updated CSG ID) of a network node, such as the target CSG cellat 810. The source HeNB may update the WTRU with the currentidentification (i.e., valid or updated CSG ID) of the target CSG cell at815. The source HeNB may initiate a second transfer of the WTRU from thesource HeNB to the target CSG cell at 820. The initiation may be basedat least in part on the current identification (valid CSG ID) and thefailed first transfer of the WTRU from the source HeNB to the target CSGcell.

In an embodiment, the WTRU may update its CSG ID mappings (e.g., map toa specific CSG ID with carrier frequency band) should the source HeNBprovides the new/corrected target CSG cell ID information in thehandover command via a RRCConnectionReconfiguration, for example.

In another embodiment, the WTRU may update CSG ID mappings after actingupon a measurement requests configured through theRRCConnectionReconfiguration message or without receiving a measurementrequest. In another embodiment, the WTRU may update its allowed CSGlist, which includes the identities of CSG cells with which the WTRU maybe permitted access.

Although features and elements are described above in particularcombinations, each feature or element can be used alone without theother features and elements or in various combinations with or withoutother features and elements. The methods or flow charts provided hereinmay be implemented in a computer program, software, or firmwareincorporated in a computer-readable storage medium for execution by ageneral purpose computer or a processor. Examples of computer-readablestorage mediums include a read only memory (ROM), a random access memory(RAM), a register, cache memory, semiconductor memory devices, magneticmedia such as internal hard disks and removable disks, magneto-opticalmedia, and optical media such as CD-ROM disks, and digital versatiledisks (DVDs). A processor in association with software may be used toimplement a radio frequency transceiver for use in a WTRU, UE, terminal,base station, RNC, or any host computer.

Suitable processors include, by way of example, a general purposeprocessor, a special purpose processor, a conventional processor, adigital signal processor (DSP), a plurality of microprocessors, one ormore microprocessors in association with a DSP core, a controller, amicrocontroller, Application Specific Integrated Circuits (ASICs), FieldProgrammable Gate Arrays (FPGAs) circuits, any other type of integratedcircuit (IC), and/or a state machine.

A processor in association with software may be used to implement aradio frequency transceiver for use in a WTRU, user equipment (UE),terminal, base station, radio network controller (RNC), or any hostcomputer. The WTRU may be used in conjunction with modules, implementedin hardware and/or software, such as a camera, a video camera module, avideophone, a speakerphone, a vibration device, a speaker, a microphone,a television transceiver, a hands free headset, a keyboard, a Bluetooth®module, a frequency modulated (FM) radio unit, a liquid crystal display(LCD) display unit, an organic light-emitting diode (OLED) display unit,a digital music player, a media player, a video game player module, anInternet browser, and/or any wireless local area network (WLAN) or UltraWide Band (UWB) module.

What is claimed is:
 1. A serving base station configured to serve awireless transmit/receive unit (WTRU), the serving base stationcomprising: a transmitter configured to transmit an indication, to aWTRU, that the WTRU is in an area that potentially contains at least oneclosed subscriber group (CSG) cell to which the WTRU is allowed toconnect; a receiver configured to receive, from the WTRU in response tothe transmitted indication, a first measurement report including aphysical layer cell identity (PCI) of a target CSG cell detected by theWTRU; the transmitter further configured to transmit, in response to thereceived first measurement report, a message to the WTRU indicating thatthe WTRU is to read system information (SI) of the target CSG cell; thereceiver further configured to receive, in response to the transmittedmessage, a second measurement report for the target CSG cell includinginformation read from the SI; and a processor configured to initiate, inresponse to the received second measurement report, a handover of theWTRU to the target CSG cell.
 2. The serving base station of claim 1,wherein the first measurement report includes information from a scan ofall frequencies in supported bands.
 3. The serving base station of claim1, wherein the first measurement report includes information from a scanof CSG dedicated frequencies.
 4. The serving base station of claim 1,wherein the first measurement report includes information from a scan offrequencies provided to the WTRU by the serving base station.
 5. Theserving base station of claim 1, wherein the first measurement reportindicates that the PCI is an unvisited PCI.
 6. The serving base stationof claim 1, wherein the second measurement report is included in a radioresource control (RRC) message.
 7. The serving base station of claim 1,wherein the indication includes configuration information that includesat least one identifier associated with the at least one CSG cell. 8.The serving base station of claim 1, wherein: the receiver is furtherconfigured to receive, from the WTRU, a capability indication indicatingthat the WTRU is configured to connect to CSG cells, and in response thereceived capability indicator, the transmitter is configured to transmitthe indication, to the WTRU, that the WTRU is in the area thatpotentially contains the at least one CSG cell.
 9. The serving basestation of claim 1, wherein the indication indicates that the at leastone CSG cell is potentially proximate to the WTRU based on a location ofthe WTRU.
 10. A method implemented in a serving base station configuredto serve a wireless transmit/receive unit (WTRU), the method comprising:transmitting an indication, to the WTRU, that the WTRU is in an areathat potentially contains at least one closed subscriber group (CSG)cell to which the WTRU is allowed to connect; receiving, from the WTRUin response to the transmitted indication, a first measurement reportincluding a physical layer cell identity (PCI) of a target CSG celldetected by the WTRU; transmitting, in response to the received firstmeasurement report, a message to the WTRU indicating that the WTRU is toread system information (SI) of the target CSG cell; receiving, inresponse to the transmitted message, a second measurement report for thetarget CSG cell including information read from the SI; and initiating ahandover of the WTRU to the target CSG cell.
 11. The method of claim 10,wherein the first measurement report includes information from a scan ofall frequencies in supported bands.
 12. The method of claim 10, whereinthe first measurement report includes information from a scan of CSGdedicated frequencies.
 13. The method of claim 10, wherein the firstmeasurement report includes information from a scan of frequenciesprovided to the WTRU by the serving base station.
 14. The method ofclaim 10, wherein the first measurement report indicates that the PCI isan unvisited PCI.
 15. The method of claim 10, wherein the secondmeasurement report is included in a radio resource control (RRC)message.
 16. The method of claim 10, wherein the indication includesconfiguration information that includes at least one identifierassociated with the at least one CSG cell.
 17. The method of claim 10,further comprising: receiving a capability indication, from the WTRU,indicating that the WTRU is configured to connect to CSG cells, and inresponse the received capability indicator, transmitting the indication,to the WTRU, that the WTRU is in the area that potentially contains theat least one CSG cell.
 18. The method of claim 10, wherein theindication indicates that the at least one CSG cell is potentiallyproximate to the WTRU based on a location of the WTRU.
 19. A wirelesstransmit/receive unit (WTRU) comprising: a receiver configured toreceive an indication, from a serving base station, that the WTRU is inan area that potentially contains at least one closed subscriber group(CSG) cell to which the WTRU is allowed to connect; a transmitterconfigured to transmit, in response to the received indication, a firstmeasurement report including a physical layer cell identity (PCI) of apotential CSG cell to the serving base station; the receiver furtherconfigured to receive, in response to the transmitted first measurementreport, a message from the serving base station indicating that the WTRUis to acquire system information (SI) of the potential CSG cell; atleast one processor configured to read information from the acquired SI;and the transmitter further configured to transmit, in response to thereceived message, a second measurement report for the potential CSG cellincluding the information read from the acquired SI.
 20. The WTRU ofclaim 19, wherein the receiver further is configured to start, inresponse to a network triggered event, searching for the at least oneCSG cell.